[controller] replace reference of controller with pointer

[Irving-cl]

This PR changes the reference of Ncp::HostRcp inside all modules
to a pointer to Ncp::HostRcp. Instead of passing the reference of
Ncp::HostRcp to all modules in their contructors, this PR changes
it as passing a pointer in the Init of these modules.

This PR is also a subset of #2283. This change is required because:
Currently there is an instance of Ncp::HostRcp as a member of the
main class Application. Most modules inside Application have a
reference to the instance and the reference is passed to these modules
in their constructor (in Application's initialization list).
However, in the NCP case, Ncp::HostRcp shouldn't be contructed at
all. So updating the reference to pointer allows Application to not
initialize these modules in NCP case and initialize a different Host.

[codecov]

Codecov Report

Attention: Patch coverage is 82.14286% with 15 lines in your changes are missing coverage. Please review.

Project coverage is 39.94%. Comparing base (2b41187) to head (9786890).
Report is 668 commits behind head on main.

Files	Patch %	Lines
src/sdp_proxy/discovery_proxy.cpp	45.45%	6 Missing ⚠️
src/trel_dnssd/trel_dnssd.cpp	50.00%	5 Missing and 1 partial ⚠️
src/border_agent/border_agent.cpp	75.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2299       +/-   ##
===========================================
- Coverage   55.77%   39.94%   -15.84%     
===========================================
  Files          87       90        +3     
  Lines        6890     9811     +2921     
  Branches        0      722      +722     
===========================================
+ Hits         3843     3919       +76     
- Misses       3047     5693     +2646     
- Partials        0      199      +199     

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[superwhd]

I think the two-step initialization (constructor + Init()) is a bit more error-prone than the one-step initialization.

What about refactor it in a different way: Define interfaces for each component and let the RCP-based implementation store the reference to the RcpHost while the NCP one doesn't.